VC中如何将数组转换为IStream流对象?
VC中如何将数组转换为IStream流对象?
我目前的方法:
创建全局内存,将数组内容拷贝到全局内存,再使用全局内存创建流(在VC中我只知道一个CreateStreamOnHGlobal()函数,惭愧!).这样虽然能达到目的,但是存在一个这样的问题:数组存在两个拷贝,一个是原来的数组本身,二个是全局内存里的拷贝.
我的问题是:怎样使用数组本身直接创建流,是流直接指向源数组呢?别告诉我换成Java,或者.Net哦,换了我就没有问题了,哈哈.
期待您的回复!

[解决办法]

C/C++ code

 
 // CVFStream 
 CVFStream::CVFStream() 
 { 
   m_filehand = NULL; 
 } 
  
 HRESULT CVFStream::FinalConstruct() 
 { 
   return S_OK; 
 } 
  
 void CVFStream::FinalRelease() 
 { 
   if( m_filehand != NULL && m_filehand != INVALID_HANDLE_VALUE) 
   { 
     CloseHandle(m_filehand); 
   } 
 } 
  
 void  CVFStream::SetServPath(const std::string& path) 
 { 
   m_servpath = path; 
 } 
  
 HRESULT CVFStream::Read(void *pv, ULONG cb, ULONG *pcbRead) 
 { 
   if(m_filehand == NULL) 
   { 
     m_filehand = OpenServFile(m_servpath); 
   } 
  
   if(m_filehand == INVALID_HANDLE_VALUE) 
   { 
     *pcbRead = 0; 
     return S_FALSE; 
   } 
  
   DWORD copyed; 
   if(!ReadFile(m_filehand, pv, cb, &copyed, NULL)) 
   { 
     return GetLastError(); 
   } 
  
   if(copyed  < cb) 
   { 
     CloseHandle(m_filehand); 
     m_filehand = INVALID_HANDLE_VALUE; 
   } 
  
   if(pcbRead != NULL) 
   { 
     (*pcbRead) = copyed; 
   } 
  
   return S_OK; 
 } 
  
 HRESULT CVFStream::Write(void const *pv, ULONG cb, ULONG *pcbWritten) 
 { 
   return E_ACCESSDENIED; 
 } 
  
 HRESULT CVFStream::Seek(LARGE_INTEGER dlibMove, DWORD dwOrigin, ULARGE_INTEGER* plibNewPosition) 
 { 
   return E_NOTIMPL; 
 } 
  
 HRESULT CVFStream::SetSize(ULARGE_INTEGER libNewSize) 
 { 
   return E_ACCESSDENIED; 
 } 
  
 HRESULT CVFStream::CopyTo(IStream *pstm, ULARGE_INTEGER cb,  
             ULARGE_INTEGER *pcbRead, ULARGE_INTEGER *pcbWritten) 
 { 
   return E_NOTIMPL; 
 } 
  
 HRESULT CVFStream::Commit(DWORD grfCommitFlags) 
 { 
   return E_NOTIMPL; 
 } 
  
 HRESULT CVFStream::Revert(void) 
 { 
   return E_NOTIMPL; 
 } 
  
 HRESULT CVFStream::LockRegion(ULARGE_INTEGER libOffset, ULARGE_INTEGER cb, DWORD dwLockType) 
 { 
   return E_NOTIMPL; 
 } 
  
 HRESULT CVFStream::UnlockRegion(ULARGE_INTEGER libOffset, ULARGE_INTEGER cb, DWORD dwLockType) 
 { 
   return E_NOTIMPL; 
 } 
  
 HRESULT CVFStream::Stat(STATSTG *pstatstg, DWORD grfStatFlag) 
 { 
   return E_NOTIMPL; 
 } 
  
 HRESULT CVFStream::Clone(IStream **ppstm) 
 { 
   return E_NOTIMPL; 
 } 
  
 HANDLE CVFStream::OpenServFile(const std::string& path) 
 { 
   std::string localpath = theCmd::Instance().GetLocalMapFile(path); 
   CA2T tlocalpath(localpath.c_str()); 
   return CreateFile(tlocalpath, FILE_READ_DATA, FILE_SHARE_READ,  
     NULL, OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL, NULL); 
 }